(1) Field of the Invention
This invention relates to a taping apparatus and, more particularly, to such an apparatus which employs dual tape applicator mechanisms for applying different ones of a pair of tapes in precise alignment on opposite sides of, and at predetermined spaced intervals along, a supply of indexably advanced strip stock, such as in the form of plastic film.
(2) Background of the Invention
In the manufacture of one particular type of flat cable, two precisely offset arrays of rectangularly shaped conductors are separated by a center film, with each array being bonded only to the respectively adjacent one of two mutually disposed adhesive-coated outer films. Prior to laminating the conductors between the center and outer films, a separate narrow insulative tape, such as of polyester plastic, is positioned transversely across, and at least lightly bonded to, each side of the center film at each of a spaced array of predetermined terminating sites along the subsequently fabricated cable, such as at intervals on the order of 5, 10 or 15 feet. With these tapes being chosen to be of a material that does not adhere to either the adjacent conductors or adhesive-coated outer films, they advantageously allow the respective portions of the conductors co-extensive therewith to be readily separated from the center film. This greatly facilitates the subsequent connectorization of the cable at such terminating sites.
In view of the function of such tapes, it becomes readily apparent that each corresponding pair thereof must normally be precisely aligned on opposite sides of the center film. This is particularly imperative when the tapes are initially of relatively narrow width (e.g., on the order of 1/2 to 1" in width), and when each pair of tapes, as secured to the film, and incorporated in a fabricated cable, are laterally bisected so as to provide both leading end and trailing end pairs thereof. Each such bisected tape is thus seen to be of only one-half its original width. For further details relating to the features and advantages of such a uniquely constructed cable, attention is directed to a co-pending application of W. A. Elliott and T. J. Taylor, Ser. No. 106,599, filed Dec. 26, 1978, and assigned to the same assignee as the present invention.
When utilizing a conventional automated tape applicator mechanism of the type of primary concern herein for taping the surfaces of articles, such as plastic films, which inherently have no rigidity, a solid backing, or platen, is required to support the film on the side thereof opposite the taping mechanism. This has presented a number of problems heretofore with respect to applying transversely oriented tapes on opposite sides of indexably advanced film in not only precisely aligned pairs, but in a rapid manner.
Considered more specifically, tape applicator mechanisms of the type in question cannot practically, and certainly not reliably, function as a platen for a corresponding, opposite film-side mechanism in alignment therewith, whether such mechanisms would be actuated simultaneously, or alternately. As such, different techniques have been used or proposed heretofore to effect a film-taping operation of the type of primary concern herein. One such technique has involved the utilization of a single tape applicator mechanism for applying a first spaced array of transversely oriented tapes on one side of an indexably advanced film, with the latter thereafter either being twisted 180.degree., or the relative positions of the supply and take-up reels being reversed, or both, so that upon the film again being advanced past the single applicator mechanism a second array of tapes will be applied to the opposite side of the film. This is not only a time-consuming and costly fabrication process but, more importantly, makes it almost impossible, regardless of the degree of control attainable over tape advancement, to insure that the film will always be stopped at the same corresponding points on opposite sides thereof during the two independent taping operations so as to achieve consistently reliable registration of the tapes, in pairs. Further compounding the problem in this regard is the fact that many films or webs, particularly when of thin plastic material, have a tendency to stretch non-uniformly by at least small amounts in being indexably advanced between two spaced points.
It has also been appreciated heretofore that two tape applicator mechanisms of the type in question could be positioned on opposite sides of, and staggered (i.e., offset) longitudinally along an indexably advanced film, such that respectively associated, and permanently positioned, platens could be aligned with each applicator mechanism on the side of the film opposite thereto. With such an arrangement, it is appreciated that the film would have to be stopped at each of the two longitudinally spaced stations in order to effect the securement of opposite side pairs of tapes to the film in hopefully aligned registration. Such a double-stop taping technique, as in the case with the aforementioned dual-pass taping technique utilizing a single-applicator mechanism, is seen to require separate film advancement dwell periods in order to apply each aligned pair of tapes to the film. This not only places what may often be undesirable limits on the time required to complete a given taping operation, but also poses serious problems in achieving consistently precise control over top side-bottom side tape registration, regardless of the chosen speed for film advancement.